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PARK, HYEONG CHEOL,KIM, HUN,KOO, SUNG CHEOL,PARK, HEE JIN,CHEONG, MI SUN,HONG, HYEWON,BAEK, DONGWON,CHUNG, WOO SIK,KIM, DOH HOON,BRESSAN, RAY A.,LEE, SANG YEOL,BOHNERT, HANS J.,YUN, DAE-JIN Blackwell Publishing Ltd 2010 Plant, cell and environment Vol.33 No.11
<P>ABSTRACT</P><P>Sumoylation is a post-translational regulatory process in diverse cellular processes in eukaryotes, involving conjugation/deconjugation of small ubiquitin-like modifier (SUMO) proteins to other proteins thus modifying their function. The PIAS [protein inhibitor of activated signal transducers and activators of transcription (STAT)] and SAP (scaffold attachment factor A/B/acinus/PIAS)/MIZ (SIZ) proteins exhibit SUMO E3-ligase activity that facilitates the conjugation of SUMO proteins to target substrates. Here, we report the isolation and molecular characterization of <I>Oryza sativa</I> SIZ1 (OsSIZ1) and SIZ2 (OsSIZ2), rice homologs of <I>Arabidopsis</I> SIZ1. The rice SIZ proteins are localized to the nucleus and showed sumoylation activities in a tobacco system. Our analysis showed increased amounts of SUMO conjugates associated with environmental stresses such as high and low temperature, NaCl and abscisic acid (ABA) in rice plants. The expression of <I>OsSIZ1</I> and <I>OsSIZ2</I> in <I>siz1-2 Arabidopsis</I> plants partially complemented the morphological mutant phenotype and enhanced levels of SUMO conjugates under heat shock conditions. In addition, ABA-hypersensitivity of <I>siz1-2</I> seed germination was partially suppressed by <I>OsSIZ1</I> and <I>OsSIZ2.</I> The results suggest that rice SIZ1 and SIZ2 are able to functionally complement <I>Arabidopsis</I> SIZ1 in the SUMO conjugation pathway. Their effects on the <I>Arabidopsis</I> mutant suggest a function for these genes related to stress responses and stress adaptation.</P>
<P>SIZ1 is a SUMO E3 ligase that facilitates conjugation of SUMO to protein substrates. siz1-2 and siz1-3 T-DNA insertion alleles that caused freezing and chilling sensitivities were complemented genetically by expressing SIZ1, indicating that the SIZ1 is a controller of low temperature adaptation in plants. Cold-induced expression of CBF/DREB1, particularly of CBF3/DREB1A, and of the regulon genes was repressed by siz1. siz1 did not affect expression of ICE1, which encodes a MYC transcription factor that is a controller of CBF3/DREB1A. A K393R substitution in ICE1 [ICE1(K393R)] blocked SIZ1-mediated sumoylation in vitro and in protoplasts identifying the K393 residue as the principal site of SUMO conjugation. SIZ1-dependent sumoylation of ICE1 in protoplasts was moderately induced by cold. Sumoylation of recombinant ICE1 reduced polyubiquitination of the protein in vitro. ICE1(K393R) expression in wild-type plants repressed cold-induced CBF3/DREB1A expression and increased freezing sensitivity. Furthermore, expression of ICE1(K393R) induced transcript accumulation of MYB15, which encodes a MYB transcription factor that is a negative regulator of CBF/DREB1. SIZ1-dependent sumoylation of ICE1 may activate and/or stabilize the protein, facilitating expression of CBF3/DREB1A and repression of MYB15, leading to low temperature tolerance.</P>
Orsini, Francesco,D'Urzo, Matilde Paino,Inan, Gunsu,Serra, Sara,Oh, Dong-Ha,Mickelbart, Michael V.,Consiglio, Federica,Li, Xia,Jeong, Jae Cheol,Yun, Dae-Jin,Bohnert, Hans J.,Bressan, Ray A.,Maggio, Al Oxford University Press 2010 Journal of experimental botany Vol.61 No.13
<P>Salinity is an abiotic stress that limits both yield and the expansion of agricultural crops to new areas. In the last 20 years our basic understanding of the mechanisms underlying plant tolerance and adaptation to saline environments has greatly improved owing to active development of advanced tools in molecular, genomics, and bioinformatics analyses. However, the full potential of investigative power has not been fully exploited, because the use of halophytes as model systems in plant salt tolerance research is largely neglected. The recent introduction of halophytic <I>Arabidopsis</I>-Relative Model Species (ARMS) has begun to compare and relate several unique genetic resources to the well-developed <I>Arabidopsis</I> model. In a search for candidates to begin to understand, through genetic analyses, the biological bases of salt tolerance, 11 wild relatives of <I>Arabidopsis thaliana</I> were compared: <I>Barbarea verna, Capsella bursa-pastoris, Hirschfeldia incana, Lepidium densiflorum, Malcolmia triloba, Lepidium virginicum, Descurainia pinnata, Sisymbrium officinale, Thellungiella parvula, Thellungiella salsuginea</I> (previously <I>T. halophila</I>)<I/>, and <I>Thlaspi arvense</I>. Among these species, highly salt-tolerant (<I>L. densiflorum</I> and <I>L. virginicum</I>) and moderately salt-tolerant (<I>M. triloba</I> and <I>H. incana</I>) species were identified. Only <I>T. parvula</I> revealed a true halophytic habitus, comparable to the better studied <I>Thellungiella salsuginea</I>. Major differences in growth, water transport properties, and ion accumulation are observed and discussed to describe the distinctive traits and physiological responses that can now be studied genetically in salt stress research.</P>
Molecular genetics has confirmed older research and generated new insights into the ways how plants deal with adverse conditions. This body of research is now being used to interpret stress behavior of plants in new ways, and to add results from most recent genomicsbased studies. The new knowledge now includes genome sequences of species that show extreme abiotic stress tolerances, which enables new strategies for applications through either molecular breeding or transgenic engineering. We will highlight some physiological features of the extremophile lifestyle, outline emerging features about halophytism based on genomics, and discuss conclusions about underlying mechanisms.
<P>A mutation of AtSOS1 (Salt Overly Sensitive 1), a plasma membrane Na<SUP>+</SUP>/H<SUP>+</SUP>-antiporter in <I>Arabidopsis thaliana,</I> leads to a salt-sensitive phenotype accompanied by the death of root cells under salt stress. Intracellular events and changes in gene expression were compared during a non-lethal salt stress between the wild type and a representative SOS1 mutant, <I>atsos1-1,</I> by confocal microscopy using ion-specific fluorophores and by quantitative RT-PCR. In addition to the higher accumulation of sodium ions, <I>atsos1-1</I> showed inhibition of endocytosis, abnormalities in vacuolar shape and function, and changes in intracellular pH compared to the wild type in root tip cells under stress. Quantitative RT-PCR revealed a dramatically faster and higher induction of root-specific Ca<SUP>2+</SUP> transporters, including several CAXs and CNGCs, and the drastic down-regulation of genes involved in pH-homeostasis and membrane potential maintenance. Differential regulation of genes for functions in intracellular protein trafficking in <I>atsos1-1</I> was also observed. The results suggested roles of the SOS1 protein, in addition to its function as a Na<SUP>+</SUP>/H<SUP>+</SUP> antiporter, whose disruption affected membrane traffic and vacuolar functions possibly by controlling pH homeostasis in root cells.</P>
Ali, Akhtar,Raddatz, Natalia,Aman, Rashid,Kim, Songmi,Park, Hyeong Cheol,Jan, Masood,Baek, Dongwon,Khan, Irfan Ullah,Oh, Dong-Ha,Lee, Sang Yeol,Bressan, Ray A.,Lee, Keun Woo,Maggio, Albino,Pardo, Jose American Society of Plant Biologists 2016 Plant Physiology Vol.171 No.3
<P>A crucial prerequisite for plant growth and survival is the maintenance of potassium uptake, especially when high sodium surrounds the root zone. The Arabidopsis HIGH-AFFINITY K+ TRANSPORTER1 (HKT1), and its homologs in other salt-sensitive dicots, contributes to salinity tolerance by removing Na+ from the transpiration stream. However, TsHKT1; 2, one of three HKT1 copies in Thellungiella salsuginea, a halophytic Arabidopsis relative, acts as a K+ transporter in the presence of Na+ in yeast (Saccharomyces cerevisiae). Amino-acid sequence comparisons indicated differences between TsHKT1; 2 and most other published HKT1 sequences with respect to an Asp residue (D207) in the second pore-loop domain. Two additional T. salsuginea and most other HKT1 sequences contain Asn (N) in this position. Wild-type TsHKT1; 2 and altered AtHKT1 (AtHKT1(N-D)) complemented K+-uptake deficiency of yeast cells. Mutant hkt1-1 plants complemented with both AtHKT1(N-D) and TsHKT1; 2 showed higher tolerance to salt stress than lines complemented by the wild-type AtHKT1. Electrophysiological analysis in Xenopus laevis oocytes confirmed the functional properties of these transporters and the differential selectivity for Na+ and K+ based on the N/D variance in the pore region. This change also dictated inward-rectification for Na+ transport. Thus, the introduction of Asp, replacing Asn, in HKT1-type transporters established altered cation selectivity and uptake dynamics. We describe one way, based on a single change in a crucial protein that enabled some crucifer species to acquire improved salt tolerance, which over evolutionary time may have resulted in further changes that ultimately facilitated colonization of saline habitats.</P>
Narasimhan, Meena L.,Coca, Maria A.,Jin, Jingbo,Yamauchi, Toshimasa,Ito, Yusuke,Kadowaki, Takashi,Kim, Kyeong-Kyu,Pardo, Jose M,Damsz, Barbara,Hasegawa, Paul M.,Yun, Dae-Jin,Bressan, Ray A. Plant molecular biology and biotechnology research 2005 Plant molecular biology and biotechnology research Vol.2005 No.
The antifungal activity of the PR-5 family of plant defense proteins has been suspected to involve specific plasma membrane component(s) of the fungal target. Osmotin is a tobacco PR-5 family protein that induces apoptosis in the yeast Saccharomyces cerevisiae. We show here that the protein encoded by ORE20/PHO36(YOL002c), a seven transmembrane domain receptor-like polypeptide that regulates lipid and phosphate metabolism, is an osmotin binding plasma mrmbrane protein that is required for full sensitivity to osmotin. PHO36 functions upstream of RAS2 in the osmotin-induced apoptotic pathway. The mammalian homolog of PHO36 is a receptor for the hormone adiponectin and regulates cellular lipid and sugar metabolism. OS-motion and adiponectin, the corresponding "receptor" binding proteins, do not share sequence similarity. However, the β barrel domain of both proteins can be overlapped, and osmotin, like adiponectin, activates AMP kinase in C2C12 myocytes via adiponectin receptors.
<P>In the last 100 years, agricultural developments have favoured selection for highly productive crops, a fact that has been commonly associated with loss of key traits for environmental stress tolerance. We argue here that this is not exactly the case. We reason that high yield under near optimal environments came along with <I>hypersensitization</I> of plant stress perception and consequently <I>early activation</I> of stress avoidance mechanisms, such as slow growth, which were originally needed for survival over long evolutionary time periods. Therefore, mechanisms employed by plants to cope with a stressful environment during evolution were overwhelmingly geared to avoid detrimental effects so as to ensure survival and that plant stress “tolerance” is fundamentally and evolutionarily based on “avoidance” of injury and death which may be referred to as evolutionary avoidance (EVOL-Avoidance). As a consequence, slow growth results from being exposed to stress because genes and genetic programs to adjust growth rates to external circumstances have evolved as a survival but not productivity strategy that has allowed extant plants to avoid extinction. To improve productivity under moderate stressful conditions, the evolution-oriented plant stress response circuits must be changed from a survival mode to a continued productivity mode or to <I>avoid</I> the evolutionary avoidance response, as it were. This may be referred to as Agricultural (AGRI-Avoidance). Clearly, highly productive crops have kept the slow, reduced growth response to stress that they evolved to ensure survival. Breeding programs and genetic engineering have not succeeded to genetically remove these responses because they are polygenic and redundantly programmed. From the beginning of modern plant breeding, we have not fully appreciated that our crop plants react overly-cautiously to stress conditions. They over-reduce growth to be able to survive stresses for a period of time much longer than a cropping season. If we are able to remove this polygenic redundant survival safety net we may improve yield in moderately stressful environments, yet we will face the requirement to replace it with either an emergency slow or no growth (dormancy) response to extreme stress or use resource management to rescue crops under extreme stress (or both).</P>
Narasimhan, Meena L.,Coca, Marı́,a A.,Jin, Jingbo,Yamauchi, Toshimasa,Ito, Yusuke,Kadowaki, Takashi,Kim, Kyeong Kyu,Pardo, José,M.,Damsz, Barbara,Hasegawa, Paul M.,Yun, Dae-Jin,Bressan, Ray Elsevier 2005 Molecular cell Vol.17 No.4
Dassanayake, Maheshi,Oh, Dong-Ha,Haas, Jeffrey S,Hernandez, Alvaro,Hong, Hyewon,Ali, Shahjahan,Yun, Dae-Jin,Bressan, Ray A,Zhu, Jian-Kang,Bohnert, Hans J,Cheeseman, John M Nature Publishing Group, a division of Macmillan P 2011 Nature genetics Vol.43 No.9
Thellungiella parvula is related to Arabidopsis thaliana and is endemic to saline, resource-poor habitats, making it a model for the evolution of plant adaptation to extreme environments. Here we present the draft genome for this extremophile species. Exclusively by next generation sequencing, we obtained the de novo assembled genome in 1,496 gap-free contigs, closely approximating the estimated genome size of 140 Mb. We anchored these contigs to seven pseudo chromosomes without the use of maps. We show that short reads can be assembled to a near-complete chromosome level for a eukaryotic species lacking prior genetic information. The sequence identifies a number of tandem duplications that, by the nature of the duplicated genes, suggest a possible basis for T. parvula's extremophile lifestyle. Our results provide essential background for developing genomically influenced testable hypotheses for the evolution of environmental stress tolerance.